Seals, and in particular air seals, are required within gas turbine engines between static and rotating components. Typically, the seals prevent leakage of cooling air from regions of high pressure to regions of low pressure. Clearly, the seals must be able to withstand and cope with the differential pressure across the seal from the region of high pressure on one side to the region of low pressure on the other. Furthermore, there may be significant accommodation and packaging problems within an engine in terms of the space available to accommodate the seal but nevertheless good sealing is required during rotating component excursions and mis-alignments during operation.
Previously labyrinth and brush seals have been used. An example of a labyrinth seal is given in United Kingdom Patent No. 803452. The labyrinth seal described in GB803452 presents a spiral incorporating folds such that the seal can be screwed into a housing and a rotating shaft held in the coil core of the spiral. The folds provide a degree of reinforcement but nevertheless the shaft can engage in a number of excursions and mis-alignments which diminish the acceptability of the seal provided. A brush seal essentially comprises bristles which extend towards the relative rotating component and provide the desired seal but are subject to wear and non-ideal sealing/support for the rotating component in operation.